text: #include "tommath_private.h"
  #ifdef BN_MP_COUNT_BITS_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* returns the number of bits in an int */
  int mp_count_bits(const mp_int *a)
  {
     int     r;
     mp_digit q;
  
     /* shortcut */
     if (MP_IS_ZERO(a)) {
        return 0;
     }
  
     /* get number of digits and add that */
     r = (a->used - 1) * MP_DIGIT_BIT;
  
     /* take the last digit and count the bits in it */
     q = a->dp[a->used - 1];
     while (q > 0u) {
        ++r;
        q >>= 1u;
     }
     return r;
  }
  #endif
  